Papers by Author: Jian Mei Chang

Abstract: In this paper the propagation of axially symmetric compression wave in an infinite transversely isotropic magnetoelectroelastic cylinder is presented. Following Pan(2002), the general boundary conditions on the surface of the magnetoelectroelastic cylinder are written by a simple vector equation that is similar to the purely elastic counterpart. By assuming the possible form of the solution, the generalized Pochhammer frequency equations are presented and the corresponding phase velocity curves in some range are given. Numerical examples are also presented to show phase velocity curves under the first 4 kinds of boundary conditions. Other boundary conditions can be studied under farther research.

Abstract: Researches of wave motion are important on theory and application. The forward problem and the backward problem are the two aspects that relate with each other. In this paper, with the combination of FEM considering BGT absorbing boundary condition for forward problem and GA method, the inversion of target’s characters in infinite area is discussed. The absorbing boundary condition is obtained through approximating the Sommerfeld radiation condition. Although the absorbing boundary condition can’t simulate the effect exactly, it can reach the limitation in the practice and has the character of solving the coupling that simplifies the calculations. Because of the use of finite element model method, the forward problems that involve special geometrical shaped scatter and multi scatters can be solved. The finite element model is used iteratively to compute the scattered field. In the inversion process, the GA method is adopted because of its advantage of global optimum search and parallel calculation. The numerical simulation examples of single and multiple show the validity of this method.

Abstract: The stability and smoothness of embankment is very important factors for the design of a new high-speed railway project. To make an accuracy prediction of the post-construction settlement, it is necessary to carry out a carefully settlement observation during the construction of embankment. The defects of traditional settlement plate, however, are well known as disturbing construction and destroyed easily by construction. In this paper, based on the application in Shi-Wu passenger dedicated line, a new type of settlement plate has been developed. The application of this new type of settlement plate in site shows that it has no any disturbs on the pavement and compaction of embankment. And measurement becomes simple and easy to operation. Accordingly, high accuracy of settlement observation can be obtained by this method, which has the value of application in high-speed railway settlement observation.

Abstract: Mode III fracture failure of a through crack in an orthotropic functionally graded strip is investigated. The shear moduli in two directions of the material are respectively assumed to vary proportionately as a definite gradient. Fourier cosine transform is used to reduce the problem to solving a Fredholm integral equation. The crack tip stress field is obtained by considering the asymptotic behavior of Bessel function. Energy density factor criterion is applied to obtain the maximum of the minimum energy density and direction of crack initiation. Numerical results are given graphically to illustrate the effects of the material property parameters and geometry criterion on the energy density factor.